Virtual machines can be provided in a computer to enhance flexibility and performance. A virtual machine typically refers to some arrangement of components (software and/or hardware) for virtualizing or emulating an actual computer, where the virtual machine can include an operating system and software applications. Virtual machines can allow different operating systems to be deployed on the same computer, such that applications written for different operating systems can be executed in different virtual machines (that contain corresponding operating systems) in the same computer. Moreover, the operating system of a virtual machine can be different from the host operating system that may be running on the computer on which the virtual machine is deployed.
In addition, a greater level of isolation is provided between or among applications running in different virtual machines. In some cases, virtual machines also allow multiple applications to more efficiently share common resources (processing resources, input/output or I/O resources, and storage resources) of the computer
For enhanced performance, virtual machines can be provided on multiple computers that are interconnected by a network. When deploying virtual machines on multiple computers, a human administrator usually has to decide at virtual machine creation time on which physical machine the virtual machine should be deployed. Often, placement of virtual machines is typically performed manually by an administrator. Although some systems are able to provide some indication to the administrator that migrating a virtual machine from one computer to another computer would be desirable, the actual selection of which computer a virtual machine should be migrated to is performed manually by the human administrator. Such manual placement of virtual machines by a human administrator is typically a time-consuming process and often does not lead to optimal or even better placement of virtual machines.
Although some techniques have been proposed to automate the migration of virtual machines across physical machines in response to various conditions, it is noted that such automated migration techniques do not consider some factors that may be relevant to effective or efficient execution of virtual machines.